If you can't limit the temperature in your dishwasher to less than the maximum ambient storage temperature of the IC's on the board, I know of no dishwasher that will exceed typical commercial limits for such devices unless you use a high-heat setting or run the dry cycle. I've done this for years and, given a cycle with which to clean the garbage out of the dishwasher, I've never regretted it. I can imagine some boards being really hard to clean out if you wash dishes without first rinsing off the food, though. In the case of VERY dirty boards, e.g. those that have been sitting outdoors for multiple years, it's advisable to remove the plastic tops of sockets, if they're present, so the dirt will be washed out from under them. If you can't do that, you're on your own. Dick ----- Original Message ----- From: "Bob Shannon" <bshannon(a)tiac.net> To: <classiccmp(a)classiccmp.org> Sent: Saturday, December 29, 2001 1:42 AM Subject: Re: Try it!!!! (Was - Re: One More PCB Dishwasher Question) below), Here's how: very the

I'm going to regret posting this, but... TXCO's come from the factory with special caps you place over them while they go through the soldering oven (modern boards don't get wave soldered anymore). Failing to place these protective caps over the TXCO's when they go through the wash cycle leads to a drifting oscillator that very often fails soon after its in the field. At Media 100 Inc, we make high-end video equipment, non-linear editors. We use very fancy TXCO's, (+/-2 ppb) and they do not survive the wash cycle without very special attention. ( I run the Test Engineering section at Media 100, and we have learned these facts emperically, by collecting failure data for many years) As the focus of the list is older machines, we need to keep things in mild like paper roll caps, etc. Advising that running old boards through the dishwasher, while sometimes safe, is not an absolutely safe thing to do. I do agree that most often, semi-modern boards will survive the process, but there are many components that will not. These components used to be much more common than they are today. But as the discussion relates to this older technology, any reccomendation to run the boards through a dishwasher should address the very real risks. How hot was the water? I don't know, its not something I can easily control. Is is possible that the 'dishwashers' used for this function commercially have been altered, and/or are connected to a lower temprature source of water? I do know that dishes come out a bit too hot to handel unless you open the door and allow them to cool. I do know its a heck of a lot hotter than any bath, after all, there is a heater element inside the dishwasher. I'm not sure its a temprature issue, as some have assumed. A dishwasher may have very powerful waterjets and a lot of vibration. The dammage may be mechanical, possibly a bonding wire detachment. But I'd like to point out once again that there are a good number of components that will be dammaged by water. Some of these have been listed in posts here already. If we accept that some components cannot be washed in this way, how can anyone defend a blanket statement that using a dishwasher on a board will be safe for that board? Simply put, you cannot. Not unless you know eash and every component on that board. All those tiny little pulse transfromers on your core memory sense amplifiers, do you know those are able to withstand this treatment? Many are not fully encapsulated, and would not be safe to treat this way. Some components (like crystals, not oscillators, just quartz crystals) cannot even be soldered safely, and are socketed for this reason. Is it s good idea to run these through your dishwasher? Lastly, storage tempratures do not assume a condensing environment, much less pressurized water jets at high tempratures, and high vibration levels. The safe storage temprature specification does not really apply here. The inability of some components to survive a water bath is. So lets agree on this... If your sure no components will be effected, go ahead and try your dishwasher. If your not absolutely sure, or if replacement parts are hard to get, don't take the risk, and use a little IPA and some elbow grease to clean your boards.

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